The present invention generally pertains to the field of flow meters, and in particular to flow meter floats for rotameters.
The regulation and metering of fluid flows are essential process steps performed in industry. For example, different caustic and corrosive acids are utilized in the manufacture of various integrated circuit devices. It can be particularly important to know quantities of the different acids transferred, and consequently, measuring and controlling flow rate can be critical to the quality of a finished product.
A widely used type of meter for these applications is a variable area flow meter or rotameter which includes a generally vertically oriented site tube. The inside diameter of the site tube varies with vertical position within the tube. The smaller inside diameter is generally proximate the flow inlet at the lower end of the tube. The inside diameter generally increases upwardly through the tube toward the flow outlet.
A "float" is placed within the tube. The float rises and descends within the tube relative to increases and decreases in flow rate of fluid through the tube respectively. The term "float" is actually a misnomer because the float is in fact more dense than the fluid and thus does not float. The float appears to float, however, due to the drag created by the upward force of the fluid flowing through the tube.
Rotameters often include a valve to control the flow rate into the site tube. Thus, the rotameter may be used to regulate the flow to a specific rate and/or measure flow over a range of flow rates.
When a rotameter is used to measure the flow of corrosive fluids, it may be desirable to use a meter containing no metallic parts, including the float. If a flow meter is equipped with a float including a metal portion, it may be desirable to replace it with an entirely non-metallic float. Additionally, it may be desirable at times to increase or decrease the range of flow rates which a rotameter having a given site tube can measure.